From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12E19C2BB55 for ; Thu, 16 Apr 2020 03:48:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F116D2076D for ; Thu, 16 Apr 2020 03:48:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391453AbgDPDsN (ORCPT ); Wed, 15 Apr 2020 23:48:13 -0400 Received: from mga03.intel.com ([134.134.136.65]:19725 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729245AbgDPDsM (ORCPT ); Wed, 15 Apr 2020 23:48:12 -0400 IronPort-SDR: /wZTq7bzQ0E2k8W/6XYNSgW1CO7wELK0a4a0VcxVCIN37lfF+DtwwWlY/1ZF2w4zwxoVHaQFTi otbtaWhvrEYg== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Apr 2020 20:48:09 -0700 IronPort-SDR: cGlxBQg4ApLsZNxgWwU23EqDS+zS9AKNnudf6RGW9EJiuVSZKIvfqcnZn9JXpx2LoQzprTKucW nOfLuM2iPAbA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,388,1580803200"; d="scan'208";a="299183864" Received: from iweiny-desk2.sc.intel.com ([10.3.52.147]) by FMSMGA003.fm.intel.com with ESMTP; 15 Apr 2020 20:48:10 -0700 Date: Wed, 15 Apr 2020 20:48:09 -0700 From: Ira Weiny To: Eric Biggers Cc: Jan Kara , linux-kernel@vger.kernel.org, "Darrick J. Wong" , Dan Williams , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , Jeff Moyer , linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH RFC 2/8] fs/ext4: Disallow verity if inode is DAX Message-ID: <20200416034809.GE2309605@iweiny-DESK2.sc.intel.com> References: <20200414040030.1802884-1-ira.weiny@intel.com> <20200414040030.1802884-3-ira.weiny@intel.com> <20200415120002.GE6126@quack2.suse.cz> <20200415191451.GA2305801@iweiny-DESK2.sc.intel.com> <20200416012901.GA816@sol.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200416012901.GA816@sol.localdomain> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Wed, Apr 15, 2020 at 06:29:01PM -0700, Eric Biggers wrote: > On Wed, Apr 15, 2020 at 12:14:52PM -0700, Ira Weiny wrote: > > On Wed, Apr 15, 2020 at 02:00:02PM +0200, Jan Kara wrote: > > > On Mon 13-04-20 21:00:24, ira.weiny@intel.com wrote: > > > > From: Ira Weiny > > > > > > > > Verity and DAX are incompatible. Changing the DAX mode due to a verity > > > > flag change is wrong without a corresponding address_space_operations > > > > update. > > > > > > > > Make the 2 options mutually exclusive by returning an error if DAX was > > > > set first. > > > > > > > > (Setting DAX is already disabled if Verity is set first.) > > > > > > > > Signed-off-by: Ira Weiny > > > > --- > > > > fs/ext4/verity.c | 3 +++ > > > > 1 file changed, 3 insertions(+) > > > > > > > > diff --git a/fs/ext4/verity.c b/fs/ext4/verity.c > > > > index dc5ec724d889..ce3f9a198d3b 100644 > > > > --- a/fs/ext4/verity.c > > > > +++ b/fs/ext4/verity.c > > > > @@ -113,6 +113,9 @@ static int ext4_begin_enable_verity(struct file *filp) > > > > handle_t *handle; > > > > int err; > > > > > > > > + if (WARN_ON_ONCE(IS_DAX(inode))) > > > > + return -EINVAL; > > > > + > > > > > > Hum, one question, is there a reason for WARN_ON_ONCE()? If I understand > > > correctly, user could normally trigger this, couldn't he? > > > > Ok. I did not think this through but I did think about this. I was following > > the code from the encryption side which issues a warning and was thinking that > > would be a good way to alert the user they are doing something wrong... > > > > I think you are right about both of them but we also need to put something in > > the verity, dax, and ... (I can't find a file in Documentation which talks > > about encryption right off) documentation files.... For verity something like. > > > > > > Verity and DAX > > -------------- > > > > Verity and DAX are not compatible and attempts to set both of these flags on a > > file will fail. > > > > > > And the same thing in the DAX doc? > > > > And where would be appropriate for the encrypt doc? > > > > Documentation/filesystems/fscrypt.rst mentions that DAX isn't supported on > encrypted files, but it doesn't say what happens if someone tries to do it > anyway. Feel free to improve the documentation. Thanks for pointing this out! Ira